1. Field of the Invention
The invention relates to an electronic component with a shift register test architecture (boundary scan).
Given the high degree of complexity of integrated circuit systems and the miniaturization achieved in the field of connection and construction techniques for electronic component groups, conventional testing methods more and more often appear achievable only at disproportionate expense. A test method that uses a test device integrated into the electronic component, which is known as a boundary scan and is standardized under IEEE Standard 1149.1, is therefore gaining increasing significance.
An essential characteristic of that test device is a shift register inserted between component terminals and circuit terminals of the component core. The shift register makes it possible to serially adjust and observe all of the component connections. Through the use of an interface, the shift register on the component can be controlled, and the shift registers of a plurality of components in one component group can be connected to make a ring structure, for instance. Test data can be shifted in and out on a component group, and when they are evaluated they enable error location that pertains both to the individual components and to their connecting lines.
The boundary scan test device of a component, which meets IEEE Standard 1149.1, can be adjusted to various operating modes through component terminals that are specific for particular testing techniques. That is described, for instance, in the publication by J. Maierhofer and B. Muller, entitled: The "JTAG Boundary-Scan" in Elektronik No 9/1989, pp. 108-113.
The above-mentioned publication explains that the boundary scan test device can optionally include a manufacturer register. This manufacturer register is 32 bits wide and contains information about manufacturer data as well as an identification code and a version number. Typically, the manufacturer register is constructed as an additional register. Since the manufacturer register is optional, and since silicon surface area is very expensive, only relatively large electronic components, in which the additional space required for the manufacturer register is not a major factor, generally include this option.